The use of radar for detecting aircraft dates back to the pre-World War II era. Developments in radar technology have led to different types and uses for radar. For Air Traffic Control (ATC) and Air Defense Control (ADC), there are two main types used: Primary (sometimes called Area) Surveillance Radar (PSR) and Secondary Surveillance Radar (SSR)/Identification Friend or Foe (IFF). PSR uses reflection from the “skin” of “targets” to detect their presence (see FIG. 1). It can be 2 dimensional (range and azimuth) or 3 dimensional (range, azimuth and altitude). SSR/IFF, on the other hand, uses an interrogation pulse sequence at one frequency to trigger a transponder on the target to respond with a related pulse sequence at a different frequency (see FIG. 2). SSR/IFF responses typically contain information (e.g. identification, altitude) regarding the interrogated aircraft.
Each of these types of radar has its own problems. PSR does not provide radar operators with information about the interrogated aircraft while SR/IFF only works with aircraft having a transponder. Currently, airports and other Air Traffic Control facilities have to be equipped with both these systems to take advantage of their respective benefits. As well, neither system can reasonably be used to detect ground-based artefacts such the baggage carts, vehicles, parked aircraft, or aircraft waiting to take off. In addition, both types of radar are required for an Air Traffic Controller to “see” both transponder-equipped and non-transponder-equipped aircraft that mix in airspace surrounding the airport/airfield (e.g. arriving and departing aircraft).
Based on the above, there is therefore a need for systems and methods which mitigate if not overcome the above noted deficiencies of the prior art.